Portrait reveals genius of Black mathematician who tracked Halley's comet

It was painted to celebrate the groundbreaking achievements of a mathematical genius who was Black and had been born into slavery. But for more than 260 years, the great scientific intellect of Francis Williams went unnoticed.

- Donna Ferguson

Now, clues exposed by an X-ray and scans of the painting have revealed the extraordinary secret that 18th-century advocates of slavery sought to keep hidden. Evidence uncovered by a Princeton historian, Prof Fara Dabhoiwala, indicates the painting is the earliest example in western art of a named Black person celebrating their status as an intellectual.

The portrait of Williams, a wealthy Jamaican polymath who was freed from slavery as a child, was bought by the furniture curator of the Victoria and Albert Museum in 1928, primarily because it depicted fine mahogany furniture.

It has long been mistaken for a satirical painting that mocks its Black subject for having the temerity to pretend to be a Georgian gentleman. But it is now thought to have been commissioned in 1760 by Williams himself to immortalise his brilliance as a trailblazing astronomer who, the clues in the painting suggest, managed to compute and witness the trajectory of Halley's comet over Jamaica in 1759.